Porous three-dimensional structures intended for usage in the medical devices are well-known nowadays.
Such structures may be, for example, a coating applied to a base [EP 0 296 335, publ. on 28.04.1988] or a compressed stack of metal sheets with the apertures which form through regular canals in the structure [US20050112397, publ. on 26.05.2005].
The disadvantages of known structures are discovered in [Karl E. MISH Orthopedic Treatment with Support on Dental Implants. Moscow, 2010, p. 347-348] and are associated with susceptibility to formation of the structure detachment, chipping and burrs.
The solution which is the closest to the technical solution claimed is the porous three-dimensional structure [WO 97/24084, publ. on 10.07.1997] made as a three-dimensional body, containing through pores and one-side open pores which are distributed evenly on the internal surface of open pores and connected to the internal surface, with sizes of pores randomly distributed in the range of 150-300 μm.
Insufficient strength and rigidity are the disadvantages of the known porous three-dimensional structure. As a rule, this structure is made on the base, and the carried out studies have shown the susceptibility to formation of the structure detachment, chipping and burrs.
There is the implant [WO 97/21393 A1, publ. on 19.06.1997] having the surface contacting with the bone tissue, containing the biologically compatible porous metal zone where bone tissue can grow into. However, the effect of this bone integration is ensured by microstructure of the metal surface area only, as the implant construction is a special cylinder without any macrogeometry promoting ingrowth of bone tissues into the implant.
There is the implant [DE 19816865 A1, publ. on 10.07.1997] containing the bioactive silicate glass coating in the zone of contact with the gum. The epithelial cells of gums can grow together with the coating on the implant ensuring its firm fit in the jaw. However, the implant construction promotes the tissue ingrowth only, without stimulation of this process and without prevention from possible ingress of infection in the implantation zone.
There is the dental cylinder-shaped implant with the base made from titanium [WO 2008/52300 A1, publ. on 08.05.2008] containing the cavity for the porous structure and the canal for introduction of medicinal drugs; the implant case is made as an external threadform spiral which is fixed by three longitudinal stiffening ribs installed inside the spiral. This dental implant is the nearest prior art reference of the first and second variants of the implant claimed.
Here the porous structure with pores sizes of 150-300 μm is installed inside the spiral.
There is the dental implant and its installation method [US6244868, publ. on 12.06.2001] being the nearest prior art reference to the third variant of the implant claimed and to the method declared, respectively. The dental implant described has the seat for a dental prosthesis and biologically compatible metal porous zone for contact with bone. The described implant is installed by means of press-fit in the jaw bone immediately after extraction of such tooth without arrest of bleeding. As by this method the dental implant is manufactured with the “averaged” biologically compatible metal porous zone, one has to widen the seat in bone for installation and this leads to the increased blood loss and traumatic operation.
The method described in [Vityaz P. A. et al. Porous Powder Materials and Goods Thereof. Minsk, Vysheyshaya Shkola, 1987, p. 114-115, 137] is the nearest prior art reference to the method claimed of manufacture of the implant claimed; this method includes formation of powder of biocompatible material (titanium or its derivatives) on the material, preferably titanium, base—a framework.
The disadvantages of the known nearest prior art references result from the above-described disadvantages of porous biologically compatible materials: layer detachment, chipping and burrs. These disadvantages of applied porous biologically compatible materials determine shortcomings of the goods made from such materials—insufficient primary stability of dental implants.